Freezing, thawing and cooking effects on quality profile assessment of green beans (cv. Win)

Results are presented of the effect of freezing followed by thawing (air and water immersion, both at environmental temperature) and cooking (traditional boiling in a covered pot) on quality profile (in terms of objective texture, colour, chlorophylls and pheophytins and sensory attributes) and structure of green beans (cv. Win). Freezing was carried out at three different rates by forced convection with liquid nitrogen vapour. Kramer shear cell (KSC) and Warner–Bratzler (WB) tests were used for objective assessment of the texture. The highest parameter values occurred in beans frozen at the highest rate and air-thawed at the slowest rate. Also, minimum alteration of the rheological behaviour of cooked beans was achieved by freezing at the highest rate. The best parameter for assessing the texture of frozen green beans after thawing and cooking was the Warner–Bratzler slope (S _WB). Coefficients of softening estimated for S _WB in the thawed beans showed that the texture of the beans frozen at −24 °C was almost four and almost five times softer than that of the beans frozen at −70 °C, for air and water thawing respectively. Frozen and thawed green beans were darker than fresh control, whereas freezing prior to cooking produced lighter-coloured beans than direct cooking. The freezing rate affected colour parameters differently depending on the process that followed. When beans were thawed, increasing the freezing rate produced lighter-coloured beans, whereas when beans were cooked, increasing the rate produced darker-coloured beans. No difference was found in sensory assessments between cooked samples frozen at −24 °C, −35 °C and −70 °C, which probably reflects the panellists' mixed preferences for quickly and slowly frozen samples. Scanning electron microscopy (SEM) revealed different degrees of mechanical damage to tissue structure, which accounted for the rheological behaviour of the beans.     

LOW TEMPERATURE ROASTING OF THAWED OR FROZEN PORK LOINS

The effects of oven temperature (93, 121, 149, or 163°C) and state (thawed or frozen) on 64 loin roasts from 8 pigs were studied. Frozen roasts required 1.3 times longer to cook, were more juicy and acceptable, and contained more moisture than thawed roasts. Roasting at 121°C produced the least losses and no difference in meat palatability from the higher oven temperatures. The 93°C oven temperature produced the least juicy but the most tender muscle with the longest cooking times and highest losses. Animals were the largest source of variance in 14 of the 19 cooking and palatability traits studied.     

Effects of cooking beef muscles from frozen or thawed states on cooking traits and palatability

Biceps femoris and longissimus lumborum steaks were cooked from either a frozen or thawed state on an electric belt grill (TBG-60 MagiKitch'n Inc., Quakertown, PA) at 93?°C to the endpoint temperature of 70?°C. Cooking loss, cooking time, Warner-Bratzler shear force (WBSF), and color (Illuminant A, L(?), a(?), b(?)) were evaluated. Trained panelists (n=6) evaluated palatability attributes on an eight-point scale for myofibrillar tenderness, juiciness, flavor, overall tenderness, and connective tissue amount (1=extremely tough, dry, bland, tough, and abundant; 8=extremely tender, juicy, intense, tender, and none). L(?), a(?), WBSF, juiciness, flavor, connective tissue amount, and overall tenderness did not differ (P>0.05) between steaks cooked from frozen and thawed states. However, thawed steaks cooked faster and had lower cooking losses than frozen steaks. The biceps femoris had higher WBSF values than the longissimus lumborum and was rated less tender by trained panelists. L(?), a(?), or b(?) values did not differ (P>0.05) between muscles. The biceps femoris needed more time to cook and had greater cooking losses than longissimus lumborum. Dimensional changes of steaks cooked to either 60 or 70?°C were studied. The width of biceps femoris steaks decreased 12.2%, and width of longissimus lumborum decreased 6.3%. Longissimus lumborum steaks became shorter (P<0.01) than biceps femoris steaks. Thickness of biceps femoris steaks decreased 25.6%, and thickness of longissimus lumborum steaks decreased 23.3%. Muscle type had a more pronounced effect on dimensional changes of steaks than endpoint temperature.     

Effect of Freezing of Beef on Subsequent Postmortem Aging and Shear Force

Seventy-two steaks were used to determine effects of freezing postrigor muscle on aging of meat and shear force. Steaks were removed from each carcass 24 hr postmortem and aged at 2°C for 2 or 6 days; or frozen at ? 30°C for 27 days, thawed 24 hr and aged 2 or 6 days at 2°C. After aging, steaks were cooked and shear force determinations made. Aging of meat reduced shear force values; however, meat aged after freezing had lower (P < 0.03) shear force values than meat aged before freezing. Meat cooked after freezing had greater (P < 0.05) cooking losses. Freezing enhances the aging process and improves shear values of meat.     

Thawing Prior to Cooking Affects Sensory, Shear Force, and Cooking Properties of Beef Patties

Patties from 6 commercial formulations were cooked to 71°C from either the frozen state or after thawing for 24 to 27 h at 4 °C to eliminate the pink/red color exhibited when cooked to 71 °C from the frozen state. Thawed patties had shorter cooking times, higher cooking yields, and lower shear force peak load and peak energy values. Patties cooked from the thawed state increased in thickness during cooking, while patties cooked from the frozen state decreased in thickness during cooking. Thawing prior to cooking increased sensory evaluation scores except for patties made with carrageenan. Thawing not only eliminated the problem of pink/red color after cooking but also improved sensory, shear force, and cooking properties of beef patties.     

EFFECT OF BLANCHING AND SULFITE TREATMENT ON THE QUALITY OF FROZEN CAULIFLOWER

The influence of blanching time and post-blanching sulfite treatment on the sensory quality and texture of frozen cauliflower were assessed after storage at -18°C for up to one year. The treated cauliflower florets, sealed in polyethylene bags, were placed in waxed paperboard cartons and frozen in a contact plate freezer at -35°C. Samples blanched for 3 min and dipped in a solution containing 1000ppm of SO₂ for 5 min gave a significantly (p<0.05) superior product even when stored for one year. The residual SO₂ content of 50 ppm found in these stored samples disappeared after a 3 min cooking in boiling water. Cauliflower texture was influenced by blanching time but the textural differences of blanched samples diminished following freezing and storage. After a 3 min cooking, the texture of all thawed samples were comparable to that of fresh cauliflower cooked for 10–12 min.     

Heating method and final temperature affect processing characteristics of beef semimembranosus muscle

The effect of thawing and cooking regimes on the processing characteristics and colour of cooked roast beef made from frozen beef cap-on inside round (semimembranosus, adductor and gracilus muscle) was investigated. After thawing in air or water, the cap was removed and the insides were pumped (110%), tumbled (30 min continuously) and then cooked in either constant-temperature water baths or baths where a 10?°C difference was maintained between the roast and the water to an internal temperature of 63 or 80?°C. Purge was higher for insides thawed in air. Insides that were cooked at a constant temperature had higher cook yields the same was seen for lower end-point temperatures. Colour of raw insides thawed in water was slightly redder than insides thawed in air. Thawing and cooking regime did not affect the colour of cooked slices but the higher the end temperature, the higher the Hunter L and the lower the Hunter a and b values. Data from this research suggests that roast beef manufacturers should evaluate thawing and cooking procedures to ensure they optimize their process.     

Programmed Freezing Affects Texture, Pectic Composition and Electron Microscopic Structures of Carrots

Raw and blanched carrots (3 min, boiling water) were frozen at ?2°C, ?3°C, ?4°C or ?5°C/min (final ?20°C or ?50°C) then thawed at 20°C or 100°C. Firmness of thawed raw carrots was: ?5°C > ?4°C > ?3°C > ?2°C/min. Effect of freezing rate on blanched carrots was less than that on raw carrots, but firmness of thawed carrots was not affected by final temperature of freezing. When raw carrots were thawed at 20°C, high methoxyl pectin decreased. Pectin decrease in blanched carrots caused by freezing was greater than that in frozen raw carrots. Effects of slow-freezing, programmed-freezing (slow + quick + slow) and quick-freezing showed quick freezing (—5°C/min) best for texture. As freezing rate decreased, drip increased. A wide difference among experimental samples in fine structure was revealed by cryo-scanning electron microscopy.     

Cooked Color in High pH Beef Patties as Related to Fat Content and Cooking from the Frozen or Thawed State

Beef patties were processed from high pH (>6.0) beef to contain 5, 10, 15, 20 or 25% fat. Patties were cooked to 71°C from the frozen or thawed state before evaluating color. Neither fat content nor state of patties when cooked exerted any major influence on color, but linear effects (p<0.01) in association with increased fat content included higher L* values and hue angles and lower a* values (15.2% reduction). Higher values for L*, b* (but not for 5% fat patties), and hue angles were observed for patties cooked thawed rather than frozen. The use of high pH beef lessened the effects of increased fat and cooking from the thawed state on increased brown color in cooked patties.     

Influence of Rapid Cooking Methods on the Survival of Trichinella spiralis in Pork Chops from Experimentally Infected Pigs

Pork chops (1.3, 2.5 or 3.8 cm thick) cooked to an internal temperature of 17 or 77°C by conventional oven, convection oven or flat grill contained no motile trichinae, whereas chops cooked to 66°C sometimes contained motile trichinae. Chops cooked by either charbroil or deep fat fry and pretreated in a microwave oven sometimes had motile trichinae even after cooking to an end point of 77°C. Chops, which had been frozen for 18 hr at -23°C and were thawed by microwave to 0°C then deep fat fried to an end point temperature, sometimes had infectious trichinae as confirmed by tests with rats and mice. Additional research is underway to verify the thermal death times and temperatures for T. spiralis larvae.     

紫苏水提物联合蒸煮处理对脆肉鲩鱼片冻藏过程中品质的影响

为了研究蒸煮处理及紫苏水提物对脆肉鲩鱼片冻藏品质的影响,以紫苏水提物浸泡的生鱼片（生鱼片组）、紫苏水提物浸泡再进行蒸煮制备的熟鱼片（熟鱼片组）、蒸馏水浸泡的生鱼片（对照组）为研究对象,研究这3 组鱼片在冻藏过程中质构、持水性、盐溶性蛋白含量、Ca2＋-ATPase活性、硫代巴比妥酸（thiobarbituric acid,TBA）值、挥发性盐基氮（total volatile base-nitrogen,TVB-N）含量和感官评分的变化。结果表明：熟鱼片及生鱼片组通过最大冰晶生成带的时间比对照组长;与对照组和生鱼片相比,熟鱼片在冻藏过程中一直维持较高的硬度、弹性、咀嚼性、TBA值和较低的持水力、盐溶性蛋白含量、TVB-N含量;与对照组相比,生鱼片组的质构特性、持水力、盐溶性蛋白含量和Ca2＋-ATPase活力更高,而TBA值和TVB-N含量更低,冻藏300 d后,生鱼片TBA值是贮藏初始时的3.85 倍,TVB-N含量低于20 mg/100 g;感官评价结果进一步表明,3 组样品感官品质在冻藏过程中不断下降,其质地、口感以及汤汁浑浊度评分从高到低依次是熟鱼片、生鱼片和对照组。研究结果证明了紫苏水提物联合蒸煮处理更有利于冻藏过程中脆肉鲩鱼片品质的维持。     

Effects of Endpoint Temperature on the Internal Color of Pork Patties of Different Myoglobin Form, Initial Cooking State, and Quality

ABSTRACT: :The effects of several parameters on the development of internal cooked color in ground pork were evaluated. Patties were made from normal or pale, soft, and exudative (PSE) pork and the pigment converted to either oxymyoglobin or deoxymyoglobin. Patties from these 4 treatment combinations were cooked from the frozen or thawed states to 5 endpoint temperatures. PSE patties and those containing oxymyoglobin exhibited premature browning as they appeared cooked and were more (P < 0.05) tan at lower temperatures than normal patties or those with deoxymyoglobin which had a slightly pink internal color at 71 °C. Percentage myoglobin denaturation increased as cooking temperatures increased (P < 0.05) for both types of meat and was greater in patties containing deoxymyoglobin than in those with oxymyoglobin. Patties cooked frozen had lower a* values (P < 0.05) than thawed patties at every endpoint temperature.     

Binding of Meat Pieces: Influence of Some Processing Factors on Binding Strength and Cooking Losses

Evacuation of the chamber of the press used to form flaked beef into a restructured meat product (patty) did not affect the binding strength of the cooked patty but under some conditions decreased the cooking loss. In studies using patty mixes containing 0–1.0% added sodium chloride, meat binding strength increased with decrease in the temperature of the mix when formed into patties over the temperature range - 1° to -5°C. The largest effect generally occurred between - 1° and -2°C. However, the effect was only noted in patties that were frozen (-30°C) before being cooked for assessment. With decrease below - 1°C of the temperature of patties when pressed, cooking losses increased for the patties without added salt but decreased for those with added salt (0.5% or 1%). Change in the pressure applied to form the patty (in the range 1.4–13.7 MPa) can affect binding strength.     

Changes in Texture of Green Peas during Freezing and Frozen Storage

The effects of freezing (still-air, air-blast, and Freon immersion freezing) and frozen storage (?5°, ?10° and ?15°C for 0 to 48 wk) on texture of cooked frozen peas were examined. Peas frozen by a Freon-12 immersion method with no appreciable damage to cell structure had firmer and more chewy sensory textural quality compared to those peas frozen by a slower freezing method. Sensory tenderness decreased initially and then increased with storage time to the maximum storage times of 6 wk in ?5°C storage, 16 wk in ?10°C storage, and 48 wk in ?15°C storage. Sensory chewiness increased initially, then remained constant with storage time except in ?15°C storage. Generally, the lower storage temperature resulted in less sensory chewiness. The correlation coefficients (r) between sensory and objective measurements for tenderness and chewiness were 0.76 and 0.88 (P < 0.05), respectively.     

FACTORS AFFECTING COLOR PROPERTIES OF BEEF PATTIES COOKED ON AN OUTDOOR GAS GRILL

Visual and instrumental color properties were obtained on beef patties cooked on an outdoor gas grill. Factors evaluated as to their influence on color were fat content, (20–28% vs 6–10%) patty handling prior to cooking (fresh, thawed either as patties or bulk ground beef), endpoint in cooking (57, 66, 71C, slit in outer edge of patty during cooking showing brown color), lighting conditions and evaluation time post-cooking. Factors resulting in less pink/red color and more brown color in cooked patties were (1) higher fat content, (2) cooking bulk frozen, thawed, then pattied product, (3) higher endpoint temperature and longer time postcooking before evaluation. Termination of cooking by observing brown color in slits in patties cooked on a gas grill was not synonymous with a safe internal temperature.     

High Hydrostatic Pressure Effects on Rapid Thawing of Frozen Beef

High hydrostatic pressure (HHP) during thawing of frozen beef was investigated by measuring temperature changes in frozen beef and the pressurization fluid. Frozen ground beef sample variables were pressure levels (140, 210, 280, and 350 MPa), times (5, 15, and 30 min), sample diameters (55, 65, and 80 mm), and initial temperatures (7, 11, 18 and 22°C). Properties of cooked patties were compared between beef thawed using HHP and using conventional thawing (atmospheric pressure at 3°C). Pressures of 210 to 280 MPa provided a critical processing range that effectively thawed the beef. Sample size and initial temperature did not affect thawing rate. The lowest temperature at which the beef was efficiently thawed was-24+2°C. HHP treated beef thawed much faster than controls. HHP thawing resulted in similar color and texture to controls.     

蒸煮方式对熟制小龙虾尾肉解冻后品质的影响

采用4 种蒸煮方式（以冷水开始煮制（BC）、以沸水开始煮制（BB）、以冷水开始蒸制（SC）和以沸水开始蒸制（SB））对小龙虾进行熟制,然后将熟制小龙虾于－18 ℃冻藏30 d,再采用2 种解冻方式（静水解冻（thawing in still water,ST）和4 ℃低温解冻（low temperature thawing,LT））进行解冻,研究不同解冻和蒸煮方式对小龙虾肌肉品质的影响。以冷却至室温未经冻藏的熟制小龙虾肉为对照组。测定菌落总数、持水性、水分分布、质构特性、色度、硫代巴比妥酸反应物（thiobarbituric acid reactive substances,TBARs）值,并通过电子鼻分析和感官评价分析小龙虾肉的感官特性。结果表明：ST组中采用BC和SC蒸煮小龙虾肉的菌落总数最高,分别为4.26、4.43（lg（CFU/g））;ST组较LT组更易使小龙虾肉的水分流失,并且以冷水开始蒸煮（BC和SC）的小龙虾肉持水性优于以沸水开始蒸煮（BB和SB）的小龙虾。感官评价与质构分析的结果表明,以沸水开始蒸煮的小龙虾肉感官品质更优。与对照组相比,ST与LT组小龙虾肉亮度值、黄度值（b*）增大,红度值减小,ST组中BC、BB、SC、SB方式蒸煮小龙虾肉的b*分别为32.67、28.87、33.36、27.36,显著高于其他2 组;ST组比LT组氧化程度高,且以冷水开始蒸煮的小龙虾肉脂肪氧化程度大于以沸水开始蒸煮的小龙虾。2 种解冻方式的小龙虾肉气味差异明显,冷、热水蒸煮对小龙虾的气味影响较大。     

Evolution of quality parameters of high pressure processing (HPP) pretreated albacore (Thunnus alalunga) during long-term frozen storage

The aim of this work was to study the application of high pressure processing (HPP) before freezing for maintaining as much as possible the fresh characteristics of albacore steaks after long-term storage. HPP treatments were applied at 200 MPa for 0–6 min. Then, samples were immediately frozen (−20 °C) and stored (−20 °C) for up to 12 months. Once thawed (4 °C; 24 h), weight losses, color, texture, lipid oxidation (TBARS) and salt-soluble protein content were analyzed.After 12 months of frozen storage, 200 MPa for 6 min minimized thawing loss inherent to freezing and frozen storage and decreased TBARS (53.9%) with respect to the control. However, it resulted in changes in color (higher L*, b* and ΔE values) and texture (higher adhesiveness and springiness) and decreased the salt-soluble protein content with respect to non-pretreated samples. Nevertheless, after cooking, there were no differences in color and texture between HPP pretreated fish and the controls.     

EFFECTS OF CULTIVARS, BLANCHING TECHNIQUES, AND COOKING METHODS ON QUALITY OF FROZEN GREEN BEANS AS MEASURED BY PHYSICAL AND SENSORY ATTRIBUTES

Effects of cultivars, blanching techniques, and cooking methods on the color, texture, and sensory characteristics of frozen green beans were investigated. Provider beans were firmer than the Contender cultivar following frozen storage and cooking when evaluated instrumentally and by a sensory panel. Microwave-blanched beans were harder according to Instron measurements, and sensory scores for firmness and toughness were higher than beans blanched by boiling water or steam. Green beans blanched or cooked by microwaves had grassy aromas and strong off-flavors that were not detected in those blanched or cooked by conventional methods. Microwave cooked beans were greener and firmer than those conventionally cooked.     

黄原胶对冷冻熟面冻藏品质的影响

研究添加黄原胶对冷冻熟面质构特性和蒸煮品质的影响,并采用差示扫描量热仪(DSC)和低场核磁共振(NMR)探究了添加黄原胶对冷冻熟面冻藏过程中可冻结水含量和水分分布的影响;利用激光共聚焦显微镜(CLSM)观察了冻藏过程中蛋白质网络结构的变化。结果表明:添加黄原胶可以提高冷冻熟面的硬度、咀嚼性和拉伸性能,降低复煮损失率和吸水率,减缓在冻藏过程中质构品质和蒸煮品质的降低趋势。黄原胶的加入可以使冻藏过程中冷冻熟面的蛋白质网络结构更加连续致密,抑制深层结合水向弱结合水方向的转移,减少可冻结水的含量,从而减少冰晶的形成,减轻因冰晶带来的机械损伤,从而改善冷冻熟面的冻藏品质。